The present invention relates to a locking device to prevent intruders from sliding or removing the sliding sash of horizontal sliding windows.
Most horizontally sliding windows are constructed so that an intruder can either force the latch or gain entry by simply lifting the entire panel slightly upwardly and then pivoting the window outwardly. An example of a window constructed in this manner is Sprague, U.S. Pat. No. 3,209,411 granted Oct. 5, 1965. Sprague shows a locking member which blocks horizontal relative movement but does not prevent removal of the panel by lifting.
The problem of panel removal was addressed by Edison in U.S. Pat. No. 3,975,041 granted Aug. 17, 1976 with a device which is semi-permanent and must be removed with a screw driver each time the window is to be moved to its full opening.
The problem of sash removal is also recognized in Jay, U.S. Pat No. 4,102,545 granted July 25, 1978. This device, however, requires that a hole be drilled in the window rail and a special "winged" key be inserted through aligned openings. When not locked, the key must be removed and is subject to loss or misplacement.